Apparatus for grinding rotating eccentric knives



Feb. 13, 1951 F, F, RUAU 2,541,615

APPARATUS FOR GRINDNG ROTATING ECCENTRIC KNIVES Filed May 19, 1947 y 2 sheets-sheet 1 y 7 {QV/ F92 APPARATUS FOR GRINDING ROTATING ECCENTRIC KNIVES F. F. RUAU Feb. 13, 1951 2 Sheets-Sheet 2 Filed May 19, 1947 1 I N VENTOR waa,

Patented Feb. 11?,V 1951 APPARATUS FORr GRINDING ROTATING ECCENTRIC KNIVES Flix Frdric Ruau, London, England, assignor to Molins Machine Company Limited, London, England, a British company Application May 19, 1947, serial No. 749,003 In Great Britain May 23, 1946 1 Claim.

This invention concerns improvementsl in or relating to apparatus for grinding rotating eccentric knives, and refers particularly to grinding apparatus for use with a cutting device in which the knife is rotatably mounted and has its edge eccentric to the axis of rotation of the knife, and which during rotation executes a movement in the direction of its axis of rotation. Such a cutting device (for example the vdevice described and shown in United States Patent No. 1,850,197) is used for severing axially moving rods into lengths, for example in cigarette-making machines of the continuous rod type for cutting a moving cigarette rod into cigarette lengths. Moreover, 'the grinding apparatus with which the invention is concerned comprises a grinding element located at a grinding position adjacent a position in the path of the knife at which the rotating knife has an axial component of movement away from the grinding element, said grinding element having a grinding surface inclined at such an angle Vto the plane of the knife that successive points along the eccentric .edge of the knife touch successive points along the inclined Agrinding surface as the knife moves across the grinding element. Such apparatus willfor convenience be referred to herein as grinding apparatus of the kind described.

It is sometimes desired to produce, on a cigarette making machine, cigarettes of different lengths and this is done (with a constant rod Speed) by altering the speed of rotation of the knife, While the cut-off is also adjusted so as to alter correspondingly the amount of axial movement of the rotating knife during cutting. For example, if the speed of 'rotation is decreased so as to cut longer cigarettes, the amount of axial movement of the knife must be increased sufoiently to cause the knife to move with an axial component which is the same as the rod speed While it is passing through the rod. After such adjustment. the knife, on rotation, travels in a new path, and the position of the grinding element must also be adjusted so that its grinding surface occupies the correct position in space to be engaged by the knife in its new path.` Moreover, the ang-1e at which the grindingsureccentricity of the knife edge must be varied.

2 Y This means in effect that for proper grinding the knife must be changed whenever the setting of the out-off is adjusted for producing cigarettes of a different length.

It is, however, desirable to maintain the degree of ecoentricity, since this is chosen according to the diameter of the cigarette rod to be cut so as to ensure that the greater part of the edge of the knife is utilised in cutting, so as to give the best possible cut.

It is an object of the present invention to provide means whereby eccentric knives mayr be ground by grinding apparatus of the kind described in different settings of the cut-on so as to have as far as possible substantially the same degree of eccentricity for each setting.

According to the prese-nt invention there is provided grinding apparatus of the kind described, Wherein the grinding element is pivotally movable to different grinding positions corresponding to different paths followed by the rotating knife when the amount of axial movement of the latter is altered, the grinding element being pivotally movable about a point such that for different axial distances travelled by the nifc during grinding at said different grin-ding positions, the grinding surface is so inclined to the plane of the knife that substantially the saine degree of eccentricity of the knife edge is maintained.

The grinding element may comprisea rotatable grinding Wheel having a peripheral grinding surface.

Grinding apparatus in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure '1 is a plan of the apparatus.

Figure 2' is a section of Figure l on the line II-II.

Figure 3 shows a side elevation of cigarette rod severing apparatus to which the invention may be applied.

Figure 4 isa partial plan view of Figure 1, with the moving lparts of the mechanism shown in a different position.

Referring to the drawing, the apparatus shown is employed in conjunction with the cut-off mechanism of a cigarette-making machine of the continuous rod type, such as described and shown in U. S. Letters Patent to W. E. Molins, 1,860,197, granted May 24,1932, in which the rotating knife executes a movement to and fro in the direction of the axis of rotation. Thus as shown in Figures 3 and 4 of the drawing, a

3 main shaft 2l is carried in bearings 22, only one of which is shown. At one end of the main shaft a blade carrying bar 23 is pivoted on a pin 2L. The bar 23 is made up of two separate links bolted together by bridge pieces 25, and each' bridge piece has a pin 26 secured at its center. The pins 26 iit into holes in a yoke 2l which is carried in a bearing 23 mounted at an angle to the main shaft 2l. The inclination of the bearing 2B is adjustable by means of a quadrant 29. The cigarette rod 30 is fed through a ledger plate 3l which is illustrated diagrammatically and may be of the usual reciprocating pattern.

A knife blade 32 is clamped in a holder 33 at one end of the carrying bar 23 and a counterweight 34 is provided at the other end.

When the main shaft 2l is rotated the same carries around with it the bar 23 and the yoke 21, and owing to the angular disposition of the latter, the blade 32 receives a reciprocating movement which is equal in speed to the linear speed of the rod, and during the time the blade is cutting through the cigarette, the plane of the blade is substantially at right angles to the axis of the cigarette rod.

The grinding element comprises a grinding wheel I having a peripheral grinding 'surface 2, the wheel being rotatably mounted on, and movable with, one arm 3 of a bell-crank lever which is pivotally mounted at @l on a part of the cigarette-making machine in advance of the cut-01T considered inthe direction of movement of the cigarette rod. The other arm 5 of the bell-crank lever is spring-urged upwardly by a spring S and plunger 'l and is held in position by an adjusting cam 8, so that by turning the cam one way or the other by the knob 9 the angular adjustment of the bell-crank lever and hence of theY grinding element may be altered. A pulley I is provided for rotating the grinding wheel.

The arm on which the grinding wheel is mounted is arranged at an angle such that the peripheral grinding surface of the wheel is at an angle to the plane of the knife of the cut-off as in Figure 2, where the knife il of the cut-off is shown. It will be appreciated that this angle vis chosen so that when the knife rotates across the grinding wheel, its eccentric edge will touch successive points on the grinding surface as the knife as a whole moves axially away from the grinding wheel. Thus there is a definite relationship between the degree of eccentricity of the knife, the amount of axial movement imparted to the knife during rotation, and the angle at which the grinding surface is set.

When the cut-off mechanism is adjusted for cutting cigarettes of a different length,V the amount of axial movement imparted to the knife as it rotates is altered. The grinding wheel is moved over to a new grinding position at which the knife, as it moves in its new path, can touch the grinding surface indicated by the chain line 2 in Figure 2. This adjustment is made by turning the adjusting' cam previously mentioned, so as to move the bell-crank lever about its pivot and thus move the grinding wheel into the desired position.

The parts are so arranged, and the pivot point of the bell-crank lever is so chosen, that this pivotal movement of the grinding wheel to a new 4 grinding position alters the angle of inclination of the grinding surface as shown so as to allow for the altered distance travelled by the knife in an axial direction away from the grinding surface during grinding, so that the degree of eccentricity of the knife remains substantially the same when the knife is ground at different grinding positions for different settings of the cut-oi.

The cam 8 is held in the adjusted position by means of a serrated collar l2 fixed to the machine and engaging a similar collar i3 lixed to the cam shaft i4, the collars being urged together by a spring I5. The collar i3 is graduated to facilitate setting for different adjustments of the 'cut-off. It will be understood that a screw or other suitable adjustment may be used instead of the cam.

It is thus possible by a simple manual adjustment to alter the setting of the grinding wheel for different settings of the cut-off, without substantially altering the eccentricity of the knife, andrto grind the knife satisfactorily.

What I claim as my invention and desire to secure vby Letters Patent is:

In cutting apparat-us for use with a continuous rod cigarette machine for cutting the moving rod into lengths, the combinationv with a rotatable radial knife having an eccentric circumferential cutting edge, of mechanism imparting to said knife during rotation a movement in the direction of its axis of rotation, means connected with said mechanism to alter the amount of axial movement imparted by said mechanism to said knife, grinding apparatus comprising a grinding wheel having a substantially cylindrical peripheral grinding surface for engagement by the knife edge during its travel, said wheel being disposed adjacent a position in the path of the knife at which the knife has an axial component of movement away from the grinding wheel, the cylindrical grinding surface of the wheel being inclined to the plane of the knife, means supporting said grinding wheel for rotation on a normally fixed axis, and means adjustably mounting said supporting means for pivotal movement about a single fixed axis only to adjust said supporting means and said wheel to different grinding positions corresponding to different paths followed by the rotating knife when the amount of axial movement of the latter is altered as a result of an adjustment of setting of the knife, the said fixed axis being parallel to the 'plane of the knife and being so located that on such pivotal movement of the grinding wheel, the angle at which the grinding surface is inclined to the plane of the knife is adjusted to maintain substantially the same degree of eccentricity of the knife edge.

FLIX iiRDRIc RUAU.

REFERENCES CITED The following references are of record in the ile of this patent:

UNITED STATES PATENTS 460,406 Germany May 26, 1946 

